TECHNICAL FIELD

[0001] The present subject matter relates generally to a vehicle. More particularly but not exclusively the present subject matter relates to a fuel control system in said vehicle.

BACKGROUND

[0002] Energy consumption in vehicles is increasing rapidly. With the advancement in technology, different types of vehicles having different energy requirements are being developed by the automobile manufactures. In addition to this, many other non-conventional sources of energy are also being explored by the automobile industry to provide an efficient energy without exhausting the current conventional sources. The automobile industry is transitioning to the next level to provide reduced emission and greener vehicle in all user segments. Apart from the non-conventional source of energy, many other systems have been developed and introduced in the vehicle to control the conventional fuel usage in the vehicle. The controlled usage of fuel not only ensure reduced emission but also ensures adequate burning of the fuel. Many fuel control systems are built to ensure that the required fuel is supplied to the engine for combustion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The details are described with reference to an embodiment implemented in a vehicle along with the accompanying figures. The same numbers are used throughout the drawings to reference similar features and components.

[0004] Figure 1 exemplarily illustrates a fuel flow control system connected to an engine.

[0005] Figure 2 exemplarily illustrates the fuel flow control system.

[0006] Figure 3 exemplarily illustrates a block diagram showing the fuel flow of said control system. [0007] Figure 4(a) exemplarily illustrates the primary fuel pressure reducer.

[0008] Figure 4(b) exemplarily illustrates the secondary fuel pressure reducer. [0009] Figure 5 and figure 6 exemplarily illustrates the fuel flow control system. [00010] Figure 7 exemplarily illustrates a flowchart for the fuel flow control system.

[00011] Figure 8(a) and 8(b) exemplarily illustrates a flowchart for detecting the fuel leakage from the one or more enclosures.

DETAILED DESCRIPTION

[0001] Whenever an engine and their fuel systems are designed, the main focus is the engine performance and durability with less regard for exhaust emissions. Over the years numerous systems for controlling emissions have been evolved, for example: utilizing a catalytic converter, an exhaust gas sensor, and a fuel modulating system to control the mixture for reduced emissions. Many other devices like supplemental fuel metering, pneumatic pressure regulator, or limited throttling of the main fuel supply have been utilized to regulate the fuel flow. Additionally, performance enhancement and improved combustion efficiency have been focussed, which as a result leads to lower exhaust gas generation. Delivering the optimal quantity of fuel to the combustion chamber through precise regulation of the flow of fuel, has been an incremental challenge. In some engines, compressed gas is used as a source of fuel which is supplied in a regulated manner to the combustion chamber. The gaseous fuel which is typically liquified form is reduced through a reducer which enables regulating pressure of the supply of gas to the combustion chamber.

[0002] Conventionally, a mechanically operated fuel reducer has two stage reducers: first is a primary reducer, and second is a secondary reducer which regulates the fuel flow. In the primary reducer, the pressure is reduced from say, 6 bar to 2 bar and a constant pressure is maintained thereafter. The constant pressure of 2 bar then passes from the primary reducer to the secondary reducer. A diaphragm of the secondary reducer senses the fuel flow and vacuum variation in an engine manifold and an intake system and regulates the fuel flow. But the above- mentioned system is not able to detect and modify the amount of fuel in accordance with the change in temperature and pressure of the fuel passing from the primary reducer to the secondary reducer. Due to this, the fuel supplied to the engine is not adequate. Above-mentioned devices and systems require substantial amounts of external support equipment and electrical interconnections, which is complex, adds to weight, and is often costly.

[0003] In addition to this, the control system requirements vary with the types of fuel used, for example: liquid fuel, gaseous fuel, and the like. Mechanically operated fuel reducers control the supply of fuel based on an engine speed, throttle position and vacuum felt at the reducer outlet. With a conventional reducer setup, the fuel is drawn by the engine vacuum. Therefore, it is difficult to externally influence the fuel supply at a specific engine operating condition. With such a system, there is always a compromise between the engine performance, the emission and the fuel economy. In order to improve the quantity of the fuel supplied to the engine, an additional electronically controlled actuator is introduced between the gas reducer and the engine intake passage of the engine. However, the upstream pressure and temperature conditions of the gas supplied from the cylinder vary instantaneously and there can be a drift over the period of time. This change in upstream conditions influence the quantity of fuel metered to the engine, causing variation of the engine behaviour. Apart from this, there is a need of a system which can detect the leakage of the gaseous fuel used in the vehicle.

[0004] An objective of the present subject matter is to provide an improved fuel control system to control the flow of the fuel and a method to detect a leak of said fuel. The system as per the present invention is capable of supplying precisely metered fuel with instantaneous understanding of the gas parameters to improve the accuracy of fuel requirement calculations, and also to improve performance, fuel economy, reduces emission, has a good start ability, can detect any leak, is cost effective and safe for a user of the vehicle. The present invention is applicable to any type of vehicle, with required changes and without deviating from the scope of invention. In the present subject matter, a fuel control system for controlling the fuel supplied to an engine comprises of one or more enclosed body portion to form one or more pressure reducer; a fuel temperature-pressure sensor, said fuel temperature-pressure sensor being disposed on one or more enclosed body portion; and a flow adjuster configured to control an area of flow path of the fuel between the one or more enclosed body portion and an engine intake passage of the engine. [0005] As per an aspect of the present subject matter, one or more enclosed body portion includes a primary fuel pressure reducer, and a secondary fuel pressure reducer. Said primary fuel pressure reducer, and said secondary fuel pressure reducer are configured to have one or more diaphragm, one or more spring, and one or more lever mechanism.

[0006] As per another aspect of the present subject matter, the fuel temperature- pressure sensor is configured to be mounted on said primary fuel pressure reducer. Said fuel temperature-pressure sensor is configured to be mounted on an upstream side of said secondary fuel pressure reducer.

[0007] As per another aspect of the present subject matter, the fuel temperature- pressure sensor being fluidically connected to a fuel volume of the primary reducer. [0008] As per another aspect of the present subject matter, a sensing chamber being fluidically coupled to said primary fuel pressure reducer and fuel temperature- pressure sensor.

[0009] As per another aspect of the present subject matter, the fuel temperature- pressure sensor being configured to sense an upstream temperature and a pressure of the fuel supplied; said secondary fuel pressure reducer transmits a control signal to an electronic control unit, based on said sensed upstream temperature and pressure of the fuel supplied, and on detection of engine operating conditions; said electronic control unit is configured to give input to said flow adjuster having a fuel adjustment screw to control the flow of said fuel to engine intake passage.

[00010] As per another aspect of the present subject matter, one or more connector is disposed to connect said primary fuel pressure reducer, and said secondary fuel pressure reducer. [00011] As per another aspect of the present subject matter, a method of controlling the fuel supplied to an engine using a fuel control system, said method comprising the steps of: switching ON, said engine; supplying, fuel from a fuel storage cylinder to a primary fuel pressure reducer, said fuel storage cylinder being configured to supply the fuel at a first pre-defined pressure; setting using a control unit, a second pre-defined pressure value at an output volume in said primary fuel pressure reducer, said primary fuel pressure reducer being configured to reduce pressure of the fuel from the first pre-defined pressure to the second pre-defined pressure; after a pre-defined time stopping the fuel supply from said fuel storage cylinder to said primary fuel pressure reducer by using the control unit; using the pressure sensor, sensing variation in the second pre-defined change in pressure in said primary fuel pressure reducer to detect a leakage of said fuel by said control unit; and using the control unit, controlling said flow adjuster based on the output of a fuel temperature-pressure sensor.

[00012] As per another aspect of the present subject matter, said method comprises the steps of issuing a warning or shutting down the vehicle by said control unit, based on the condition of said engine, the control unit, and the pressure in said primary fuel pressure reducer.

[00013] As per another aspect of the present subject matter, said fuel temperature- pressure sensor being fluidically connected to a fuel volume of the primary reducer. [00014] As per another aspect of the present subject matter, said method comprises the steps of: sensing by said fuel temperature-pressure sensor, an upstream temperature and a pressure of the fuel supplied; transmitting by said secondary fuel pressure reducer, a control signal to said control unit, based on said sensed upstream temperature, pressure of the fuel supplied and on the engine operating conditions; and transmitting input by said electronic control unit to said flow adjuster having a fuel adjustment screw to control the flow of said fuel. The embodiments of the present invention will now be described in detail with reference to an embodiment in a two wheeled vehicle along with the accompanying drawings. However, the present invention is not limited to the present embodiments. The present subject matter is further described with reference to accompanying figures. It should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.

[00015] Fig.l exemplarily illustrates a fuel flow control system 100 connected to an engine 101. Fig.2 exemplarily illustrates the fuel flow control system 100. Fig.3 exemplarily illustrates a block diagram showing the fuel flow of said control system 100. The fuel flow control system 100 comprises of a one or more enclosed body portion 102, a flow adjuster 104, a fuel temperature-pressure sensor 103, a fuel storage cylinder 110. The engine 101 is provided with an intake passage 112, the intake passage 112 is fluidically connected with the fuel flow control systemlOO. The one or more enclosed body portion 102 includes a primary fuel pressure reducer 106, and a secondary fuel pressure reducer 107. The primary fuel pressure reducer 106 reduces the pressure of fuel supplied from the fuel storage cylinder 110 to a required value of pressure and maintains it thereafter. The secondary fuel pressure reducer 107 senses a downstream engine flow condition and regulates the flow of fuel supplied from the primary fuel pressure reducer 106 before it is being supplied to the engine 101. The flow adjuster 104 is configured to control an area of flow path of the fuel between the one or more enclosed body portion 102 and the engine intake passage 112. A flow adjustment screw 114 is actuated by the flow adjuster 104 to control the flow of the fuel. The flow adjuster 104 can be a fixed mechanical part or a dynamic actuator. In the present embodiment, the flow adjuster 104 is a dynamic actuator which is controlled by an Electronic Control Unit 115 (shown in fig.3). The electronic control unit 115 (shown in fig.3) analyses the engine operating conditions and gives an output signal to the flow adjuster 104 or an engine actuator based on the fuel temperature and pressure. The fuel temperature-pressure sensor 103 is fluidically connected to a fuel volume of said primary fuel pressure reducer 106 to sense the fuel temperature and pressure to control the flow of the fuel to the engine 101. However, in the present embodiment, the fuel temperature-pressure sensor 103 is fluidically connected to a fuel volume of said primary fuel pressure reducer 106. In the present embodiment, the fuel supplied to the engine 101 is a gaseous fuel. However, it can be one of the fluid fuels, liquid fuel, gaseous fuel, combination of both the liquid fuel and gaseous fuel, and the like, depending upon the configuration of the vehicle. The interaction shown between the components in the block diagram can be an electrical interaction or a mechanical interaction. Figure.3 illustrates the flow of fuel from the one or more enclosed body portion 102 to the engine 101. The fuel from the fuel storage cylinder 110 flows to the one or more enclosed body portion 102 at a predefined pressure. The fuel then goes to the fuel adjuster 104. The fuel adjuster 104 operates, based on the inputs from the control unit 115. The control unit 115 monitors the engine 101 operating condition and gives input to the flow adjuster 104 based on the fuel temperature and pressure 103. The fuel adjuster 104 then actuates the fuel adjustment screw 114 to allow the pre-determined fuel calculated to the engine 101.

[00016] Fig.4(a) exemplarily illustrates the primary fuel pressure reducer 106. The primary pressure fuel reducer 106 is connected to the fuel storage cylinder 110 (shown in figure 1) to supply fuel from said fuel storage cylinder 110 to the secondary fuel pressure reducer 107 (shown in figure 4(b)). The primary fuel pressure reducer 106 is connected to the fuel storage cylinder 110 by means of a high-pressure line 111 (shown in figure 1) to maintain a constant pressure supply to the primary fuel pressure reducer 106. One of the functions of the primary fuel pressure reducer 106 is to reduce the pressure of the fuel supplied from the fuel storage cylinder 110 (shown in figure-1) to a required value of pressure and to maintain the pressure . The pressure and temperature in the primary pressure reducer 106 can vary depending upon various factors. For example: a) pressure and temperature changes with the change in the fuel quality, b) environmental factors like humidity and the like, c) the pressure in the pressure reducer may deteriorate with time because of durability issues, d) a downstream pressure from the fuel storage cylinder can decrease, e) when vehicle runs in reserve fuel condition, the pressure of the fuel decreases, and the like. Apart from this, the pressure and temperature of the fuel changes the density of the fuel supplied to the engine which disturbs the ratio of the air-fuel mixture. Therefore, control of flow of fuel is to be regulated. So, even if the primary fuel pressure reducer 106 is calibrated at a particular pressure and temperature, it may change due to above-mentioned factors, resulting in inefficient fuel supply to the engine 101 (shown in figure 1). The primary fuel pressure reducer 106 includes a primary diaphragm (106a), a primary spring (106b), a primary lever (106c) mechanism, a primary valve seat (106d), a primary vent (106e), and a primary valve (106f). The primary vent (106e) is provided in the primary fuel pressure reducer 106 to vent out the pressure which gets built up due to the movement of the primary diaphragm (106a), and thus the vent (106e) maintains a specific volume of fuel inside the primary fuel pressure reducer 106. The high-pressure line 111 from the fuel storage cylinder 110 is connected to the primary valve (106f) (the connection is not shown in figure) of the primary fuel pressure reducer 106. The above-mentioned parts of primary fuel pressure reducer 106 are configured to work in conjunction to open and close the primary valve (106f) during operation. During the operation, the fuel storage cylinder 110 (shown in figure-1) connected to the inlet of the primary fuel pressure reducer 106, supplies fuel at a higher pressure say, 3 bar to 10 bar which can vary based on the flow requirements and the fuel stored inside said cylinder 110. The primary fuel pressure reducer 106 is configured to maintain a constant fuel pressure output say, 3 bar to 1 bar. The fuel is supplied to the volume in the primary fuel pressure reducer 106, by continuous opening and closing of the valve (106f). Further, the fuel flows to the entry of the secondary fuel pressure reducer 107 and pushes the valve (107b) (shown in fig.4(b)) to open.

[00017] Fig.4(b) exemplarily illustrates the secondary fuel pressure reducer 107. The secondary fuel pressure reducer 107 is disposed adjoining to said primary fuel pressure reducer 106 (shown in figure 4(a)) and together forms an integrated unit inside the one or more enclosed body portion 102. The secondary fuel pressure reducer 107 includes a secondary diaphragm (107a), a secondary valve (107b), a secondary lever (107c), a secondary valve seat (107d), a secondary vent (107e), and a secondary hole vent (107f). The secondary fuel pressure reducer 107 input is opened and closed with the secondary valve (107b) controlled by a mechanism which includes the secondary spring (not shown), the secondary lever (107c) and the secondary diaphragm (107a) The volume of the primary fuel pressure reducer 106 and then opens to the secondary fuel pressure reducer 107 through a passage 113. The secondary valve (107b) connects to a volume that is connected to the engine intake passage 112 (shown in figure-1) of the engine 101 (shown in figure- 1) , which makes it a part of the secondary fuel pressure reducer 107. The fuel is supplied to the volume in the primary fuel pressure reducer 106 (shown in figure- 1), by continuous opening and closing of the primary valve (106f) (shown in figure 4(a)). The fuel in the volume of the primary fuel pressure reducer 106 flows to the entry of the secondary fuel pressure reducer 107 and pushes the secondary valve (107b) to open, and then is closed by a mechanism comprising of the secondary diaphragm (107a), the secondary spring (not shown) and the secondary lever (107c). The opening and closing of the secondary valve (107b) are decided by the secondary diaphragm (107a) which senses the downstream engine air flow and operating conditions. The secondary vent (107e) is provided in the secondary fuel pressure reducer 107 to vent out the excess pressure which gets built up due to the movement of the secondary diaphragm (107a), and thus the vent maintains a specific volume of fuel inside the secondary fuel pressure reducer 107. The fuel that is a gas in present embodiment, expands to the engine downstream pressure and the gas is supplied to the engine intake passage 112 (shown in figure 1) through the flow adjuster 104 (shown in figure 2) whose area of opening is varied based on the engine operating requirements, which are set based on the predefined values. The flow adjuster 104 with the variable annular area and the fuel adjustment screw 114 (shown in figure 1) is disposed between the secondary fuel pressure reducer 107 and the engine intake system 112 (shown in figure 1) to control the flow of the fuel. The flow control system 100 is electrically connected to the electronic control unit 115 (shown in fig.3). The fuel temperature - pressure sensor 103 (shown in figure 1) is fluidically connected to the volume between the valves (106f, 107b) of the primary and the secondary fuel pressure reducer (106, 107). The fuel temperature - pressure sensor 103 (shown in figure 1) which is in contact with the fuel present in the secondary pressure reducer 107 senses the state of the fuel and gives the signal to the electronic control unit 115 (shown in fig.3) which based on the predefined parameters controls the engine actuators (not shown). The location of the fuel temperature - pressure sensor 103 (shown in figure 1) between the two- pressure reducer (106, 107) to sense the upstream temperature and pressure of the fuel supplied enables the precision of fuel metering. Further, the quality of the fuel metering by the secondary fuel pressure reducer 107 is a function of the pressure and temperature of the primary fuel pressure reducer 106, where instantaneous input of the fuel parameters improves the accuracy of fuel requirement calculations, and also helps in achieving the required air-fuel mixture. This enhances the performance, emission, pickup and mileage of the vehicle.

[00018] Fig.5 and Fig.6 exemplarily illustrates the different embodiments of the fuel flow control system 100. The control system 100 is provided with an additional sensing chamber 108 disposed at the side of the primary fuel pressure reducer 106 as shown in figure-4. The additional sensing chamber 108 is disposed between the primary fuel pressure reducer 106 and the fuel temperature-pressure sensor 103. The additional sensing chamber 108 is fluidically connected to the volume of the primary fuel pressure reducer 106 to sense the pressure of said pressure reducer 106. The additional sensing chamber 108 remains at the same pressure as that of the primary fuel pressure reducer 106. In an embodiment (shown in Fig 6), the primary fuel pressure reducer 106 and the secondary fuel pressure reducer 107 are disposed at a pre-determined distance between them. The two-pressure reducers (106, 107) are connected through a connector 109 to allow the fuel to flow from said primary reducer 106 to said secondary reducer 107, as shown in figure-6. The fuel temperature-pressure senor 103 is disposed on the side of the connector 109 to sense the pressure and temperature of the fuel flowing through the primary reducer 106 to the secondary reducer 107.

[00019] Fig.7 exemplarily illustrates a flowchart for the fuel flow control system 100. When the vehicle ignition key is switched ON, a solenoid (not shown) in the fuel storage cylinder 110 (shown in figure-1) is opened by a control unit 115 (shown in fig.3) and the fuel from fuel storage cylinder 110 (shown in figure-1) flows in the high-pressure line 111 (shown in figure-1) to reach said primary fuel pressure reducer (at step 201). The Temperature and the pressure signal say, P„ and T„ respectively are sensed by the fuel temperature-pressure sensor 103 and the signal is given to the electronic control unit 115 (shown in fig.3) (at step 202). Based on the input signal and the engine state, with predefined correction factors stored inside the control unit 115 (shown in fig.3) (at step 203), the control unit 115 gives an output to the flow actuator to control the area of opening A„ of the flow actuator disposed between the secondary fuel pressure reducer and the engine (at step 204). Whenever the Signal P„ and T„ arc changed, the control unit 115 changes the A„ of the flow actuator as required. Thereby any change in A„ changes an instantaneous fuel flow rate F„. Thus, the instantaneous fuel flow rate of the fuel is directly proportional to the measured pressure and is inversely proportional to the square root of the measured temperature. The opening of the area A„ of the flow adjuster is directly proportional to the instantaneous fuel flow rate F„ governed by equation. F„ a A„ a P„ _, T ₀

[00020] Fig.8(a) and 8(b) exemplarily illustrates a flowchart for detecting the fuel leakage from the one or more enclosures as per an additional embodiment. The leakage of the fuel, which is gaseous fuel in the present embodiment, is a problem for the safety of a user of the vehicle. So, detection of the leakage of the fuel is very important to make the vehicle safer for the user. A method for detecting the leakage of fuel and the method is implemented by the fuel control system as shown in figure-7. When the vehicle ignition key/ engine is switched ON (at step 301), the solenoid in the fuel storage cylinder 110 is opened by the control unit 115. Then, the fuel is supplied to the primary fuel pressure reducer 106 at a first pre-defined pressure (at step 302). The ppressure in the high-pressure line 111 is maintained same as the supply pressure i.e. the pressure in the fuel storage cylinder 110. The pressure in the output volume of the primary fuel pressure reducer 106 is set to a second predefined pressure value as per the setting (at step 303). The primary fuel pressure reducer 106 reduces pressure of the fuel from the first pre-defined pressure to the second pre-defined pressure (at step 304). After the ignition key has been turned On and a predetermined settling time of say, to, has passed, the solenoid (not shown) is turned OFF, thereby flow of the fuel from the solenoid to the primary reducer 106 is stopped (at step 305). The pressure in the primary fuel pressure reducer 106 at to is Po. After a fixed time, say, change in temperature is tl, the pressure is PI. The electronic control unit 115 (shown in fig.3) is configured to sense the pressures Po and PI to decides whether there is a system leakage or not. If PI is relatively out of a range defined in the control unit 115 with respect to Po, then a leakage of fuel is identified (at step 306). The flow adjuster 104 is thus controlled based on the output of a fuel temperature-pressure sensor 103 to control the fuel flow (at step 307). Based on the state of the engine and the control unit 115, a warning is sent or a vehicle shut down is executed by the control unit 115, depending on the severity of the leakage detected based on the degree of variation of the pressure and temperature in the primary fuel pressure reducer. Many other improvements and modifications may be incorporated herein without deviating from the scope of the invention.

List of Reference numerals

100: Fuel control system 101: Engine 102: Enclosed body portion of 106 and 107

103: Fuel temperature-pressure sensor of 100 104: Flow adjuster of 100 106: Primary fuel pressure reducer of 100 106(a): Primary diaphragm of 106 106(b): Primary spring of 106

106(c): Primary lever of 106 106(d): Primary valve seat of 106 106(e): Primary vent of 106 106(f): Primary valve of 106 107: Secondary fuel pressure reducer of 107

107(a): Secondary diaphragm of 107 107(b): Secondary valve of 107 107(c): Secondary lever of 107 107(d): Secondary valve seat of 107 107(e): Secondary vent of 107

107(f): Secondary hole vent of 107 (e)

108: Sensing chamber of 100 109: Connector of 106 and 107 110: Fuel storage cylinder of 100 111: High-pressure line of 110

112: Intake passage of 101 113: Passage between 106 and 107 114: Fuel adjustment screw of 104 115: Control unit